Engine starter gearing



Sept. 28, 1948. v D. L. MILLER 2,450,246

' ENGINE STARTER GEARING Filed June 21, 1946 IN VEN TOR.

WITNESS; Z J

-A RMY Patented Sept. 28, 1948 ENGINE STARTER GEARING Donald L.- Miller, Pine City,

dix Aviation Corporation,

N. Y., assignor to Ben- Elmira Heights, N. Y.,

a corporation of Delaware Application June 21, 1946, Serial No. 678,343

4 Claims.

vide a novel engine starter drive incorporating an overload release device which is eficient and reliable in operation while being simple and economical in construction.

It is another object to provide such a device in which the operative position of the starting pinion is accurately defined.

It is a further object to provide such a device including an over-running connection between the starting motor and the drive pinion.

It is another object to provide such a device including ielding means for demeshing the drive pinion and maintaining the engagement of the over-running clutch connection.

It is another object of the invention to provide a device in which all the parts of the drive are so mounted and piloted on the drive shaft that proper alignment of the parts is maintained at all rotative speeds.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which: Fig. 1' is a side elevation partl broken away and in section of a preferred embodiment of the invention, showing the parts in idle position; and

Fig. 2 is a similar view showing the parts in operative position,

In Fig. l of the drawing there is illustrated a starting motor I having a smooth extended armature shaft 2 on which a drive pinion 3 is slidably journaled for movement into and out of mesh with a gear 4 of an engine to be started.

Means for actuating the pinion from the drive shaft 2 is provided comprising a driving head 5 rigidly mounted adjacent the outer end of the drive shaft by suitable means such as a cross pin 6. The drive head 5 is provided with ratchet teeth 1 adapted to engage corresponding teeth 8 of a driving cam member 9 which is freely journalled on the drive shaft 2. A driven cam member H similarly mounted on the drive shaft is arranged to cooperate with the driving cam member 9, Cam member H has a flanged sleeve I3 suitably fixed thereon as by welding or brazing as indicated at [2, which sleeve forms a seat for one end of a yielding driving member M in the form of a cylinder of elastically deformable material such as rubber.

The opposite end of the yielding driving member l4 bears frictionally on a thimble l5 having a telescopic bearing on the sleeve I3, and rigidly attached as by welding or brazing at [6 to a flange l1 fixed as indicated at l8 to the pinion 3.

A barrel member i9 is arrangedto surround and enclose the yielding drive member l4, and is provided with an internal groove 2i receiving the peripheries of thimble I5 and pinion flange H, which are retained in the groove 2| by spinning over the end of the barrel as shown at 22.

The barrel I9 is journalled at an intermediate portion on the flange 23 of sleeve l3, the barrel being provided with a shoulder 24 forming an abutment for the flange so as to maintain the yielding driving member 14 under initial compression. The barrel has a rearwardly extending portion 25 which is preferably tapered as shown, and terminates in a radially inwardly extending flange 26 which bears on the driving shaft 2 and is adapted to engage the drivin head 5 as shown in Fig. 2 in order to limit the longitudinal movement of the barrel and its associated parts and thereby define the operative position of the pinion 3 with relation to the engine gear 4 A hardened insert or washer 21 may be interposed between the flange 26 of the barreland driving head to reduce wear.

Means for normally maintaining the parts in idle position is provided in the form of a light compression spring 28 seated at one end in the end of the barrel is and at its other end on a ring member 29 surrounding the driving head 5 so as to retain the pin 6 in position, and bearing against a shoulder 3| formed on said driving head.

In assembling the drive, the parts, with the exception of the pin 6, are inserted in order through the open end of the barrel I9, and are retained by crimping over the end of the barrel as shown at 22. When the drive is to be mounted on a motor shaft, the assembly is slid on the shaft, a tool is inserted through the opening 32 in the barrel to move back the ring 29, whereupon the pin 6 is passed through opening 32 and through the drive head 5 and shaft 2, and the ring 29 permitted to return to its normal position, thus retaining the pin 6 in locked position.

According to the present invention, the cam members 9 and H are provided with cooperating calm surfaces 33 2 3 respectively which are so inclined to the axis of the power shaft that torque the cam surfaces 33 will slide off the ends of the cam surfaces 34, thereby temporariIy breaking the torque connection between the cam members.

In the operation of the device, starting with the parts in the position shown in Fig. 1, energize.- tion of the power shaft 2 by the starting motor causes rotation of the driving head to be transmitted through the over-running clutch connection 1, 8 to the driving cam member 9. Rotation of the driving cam member causes longitudinal movement of the driven cam member II to the night, thereby moving the barrel assembly including the pinion 3 longitudinally until the pinion is fully meshed with the engine gear 4 at which time the flange 26 of the barrel engages the driving head 5 and thereby arrests the longitudinal movement of the barrel. Further rotation of the power shaft 2 causes compression and torsion of the yielding member l4 until the resistance of the engine gear 4 to rotation is overcome, and the engine is set in motion.

When the engine becomes self-operative, the acceleration of the engine gear 4 causes the pinion 3 with its associated parts to overrun the power shaft 2, which overrunning is penrnitted by the saw-tooth dental clutch I, 8; The spring 28 is thereupon operative to withdraw the parts to idle position and thereafter maintain the engagement of the clutch teeth 1, 8.

If the starter should be energized inadvertently at av time when the engine gear is rotating backwardly from a previous start and backs-fire, or for any other reason, the collision of the forwardly rotating parts of the starter mechanism with the backwardly rotating engine gear may cause excessive stresses to be developed. Should this occar, the yielding member I4 is further compressed beyond its usual operative position as shown in Fig. 2 until the ends of the driving cam surfaces 33 slip by the endsof the driven cam surfaces 34, so as to release the driving connection and prevent damage to the parts. As soon as the eXcessive forces have been dissipated, cranking. may be resumed in the usual :manner until the engine is reliably self-operative.

Although but one embodiment of the invention has been shown and described in detail it will be understood that other embodiments are possible and various changes may be made in the design and arrangements of the parts without departring from the spirit of the invention as defined in the claims appended hereto:

What is claimed is:

1. In an engine starter drive a power shaft, a [pinion slidably journalled thereon, a barrel fixed at, one end to the pinion and journall'ed at its other end on the shaft, a driving head in the barrel forming an abutment defining the operative position of the barrel and pinion, a driving cam member on the shaft connected to rotate with the driving head, a driven c'am member slidably journalled on the shaft and having an inclined connection to the driving cam member, a compressible driving connection between the driven cam member and pinion and yielding means in the barrel urging the pinion toward idle position.

2. A starter drive as set forth in claim 1 in which said compressible driving connection is so co-ordinated with the inclined connection between the cam members that the cam members lmay slip and disengage upon a predetermined overload.

3. An engine starter drive as set forth in claim I includingfurther an over-running clutch connection between the driving head and driving cam member.

4. An engine starter drive including a power shaft, a driving head fixed thereon, a pinion journalled on. the shaft and movable longitudinally into and out of mesh with a gear of an engine to be started, means including an inclined connection and a yielding torque transmitting member for connecting the \pinion for actuation by the driving head, and. means co-operating with the driving head to limit the travel of the pinion into meshed position, said inclined connection being so formed as to disconnect after a predetermined compression of the yielding member; including further an over-running clutch between the driving head and the inclined connection, and means including a spring for urging the pinion toward idle position and for maintaining the engagelm'ent of the over-running clutch.

DONALD L. MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,199,349 Sekella Apr. 30, 1940 2,203,724 Fitzgerald June 11, 1940 2,271,216 Ysskin Jan. 27, 1942 2,420,283 Buxton et al May 6, 1947 

